In the mid to late 19th century, the sine qua non of economic power was control of physical, industrial capital. The supply chain was very short, consisting of only one or two steps of industrial production: trees to lumber mills to factories to furniture. Control the factories and at the very least you have a fighting chance against the imperialist control of raw materials and emerging markets. And with an organized, unionized industrial labor force, you have the real possibility of physically controlling the factories either directly by actually taking over factories or indirectly through the threat of local and general strikes.
And the world came very close to actually trying this kind of revolution. The first Imperialist War, which was primarily a struggle for the great imperialist powers to control sources of raw materials and (to a lesser extent) emerging markets, had the secondary effect of breaking the power of industrial labor in Europe to effect any kind of revolution.
We cannot at all blame the capitalist ruling class for this failure. We should expect them to hold onto their power and privilege by any means necessary, including the deaths of tens of millions of people. Thus it has been with every ruling class in the history of humanity; we cannot expect any better of the capitalists, regardless of their propaganda. We must lay the blame, I think, at the feet of the European Democratic Socialists of the 19th and early 20th century.
The "essence" of Democratic Socialism* is, I think, the position that we should improve the position of labor within the capitalist system while preserving and maintaining the capitalist system itself. The aim is not "true" socialism: the actual control by the working class of the government and pervasive social and political constructions. The Democratic Socialist position is at least superficially admirable: their aim was, I think, very similar to Franklin Roosevelt's New Deal (except without Keynes understanding of economics), which was in its limited way moderately successful.
*In other words, it is reasonable to label this political position as "Democratic Socialism" for the purpose of discussion.
But as superficially admirable as it was, it was not really feasible without Keynes' contributions to economic theory and, on the eve of the First Imperialist War it was a position that transcended simple naivete and fell firmly into a treasonous betrayal of the working class by politicians and leaders who had promised to protect and extend the interests of the working class.
On the eve of the First Imperialist war, the specific historical conditions of capitalism in opening years of the 20th century Europe demanded a continent-wide war, as the various capitalists competed violently for access to raw materials and a hyper-exploitable population of workers to extract those raw materials. This war could only be fought by the working class itself — the idea of the capitalists themselves picking up guns and fighting each other directly was obviously ludicrous. So the Democratic Socialists were in a bind: supporting capitalism meant supporting the war, a war that would be fought by worker against worker, both in the trenches and in the factories; opposing the war meant making a decisive break with the industrial capitalist ruling class. The position of the Democratic Socialist leaders themselves was in no small part supported by a faction of capitalist class: the Democratic Leaders could no longer stay on the fence.
As history has shown us, the leaders of every socialist movement in every European country at the eve of the First Imperialist war — with the exception of Lenin's Bolsheviks and a few dissident figures such as Rosa Luxemburg and Karl Liebknecht — came down on the side of capitalism. Either they were absolutely cynical or they utterly naive and believed that the capitalist ruling class of the winning nations would be sufficiently grateful for the working class's blood and suffering on the capitalists behalf that they would offer the workers substantial concessions.
As history has shown us as well, the "winners" of the First Imperialist War showed no gratitude at all to the working class that had shed so much blood on its behalf. The close of the war saw an increase in the exploitation and oppression of the industrial workers and a catastrophic global financial crisis a mere two decades after the war's end. (Remember: a financial crisis — the Great Depression as well as today's economic catastrophe — is a failure of capitalism itself, not an "external" crisis that individual capitalists fail to adequately respond to.)
We missed two further opportunities for a relatively "easy" revolution.
In Failure of a Revolution, Sebastian Haffner documents a popular socialist uprising after Germany's humiliating defeat in the First Imperialist war. This uprising failed not just because it was opposed by the German capitalist class, but also because the socialist leaders of the time actively betrayed the people they had promised to represent and recruited and encouraged the extreme right wing to violently suppress the revolution. This right wing opposition to the popular uprising formed the seeds of Nazi Germany and an important foundation of the Second Imperialist War.
The last opportunity was the co-option of the socialist left by "Democratic Socialism" (by this time beginning to transform itself into the capitalist welfare state) in Franklin Roosevelt's New Deal. As Norman Thomas famously remarked, "Emphatically, Mr. Roosevelt did not carry out the Socialist platform, unless he carried it out on a stretcher." The co-option of the socialist left by Democratic Socialism and the formation of the capitalist welfare state is prefigured in the conflict within the labor union movement. Elena Kagan describes one aspect of this conflict in her senior thesis, To the Final Conflict: Socialism in New York City. Grasping this opportunity was a slim chance, but it was the final chance to gain the economic power necessary to fight the capitalist class toe to toe.
Now, of course, it's just too late to do things the "easy" way. The supply chain for even the simplest industry such as food production is tens of layers deep and includes thousands of interacting companies, factories, and supply and distribution channels. Even if the workers managed to decisively control all the physical industrial capital (farms, factories, trains and trucks, grocery stores) productivity would grind to a halt without the finely tuned web of relationships, promises and obligations of the global financial system, a system firmly in the hands of the capitalist class and the upper levels of the professional-managerial class who can be absolutely trusted to maintain the power and privilege of the capitalists.
If we are to have a communist revolution, it will have to follow the catastrophic and complete internal failure of the capitalist ruling class. We will have to rebuild the global industrial and productive infrastructure after it has collapsed. The price of this catastrophe and rebuilding will be immense and terrible, so terrible that I do not believe any person with the conscience, love of humanity and hatred of human suffering necessary to be what I would call a good communist could possibly contemplate actively bringing about, even if it were feasible to do so, which it probably isn't.
But the capitalist ruling class, and the contradictions inherent in capitalism, seem poised to bring about this catastrophe on itself — and, unfortunately, all of us. All we can do is (1) continue to point out that capitalism is nowhere close to the best that humanity can do, (2) build some sort of communist economic and political theory that will be applicable to conditions following capitalism apparently imminent demise and (3) create enough of an organization so that humanistic communism has sufficient social credibility and power to take control after the collapse of capitalism. We must become, I think (and if you'll pardon the hackneyed fantasy) at least metaphorically like Isaac Asimov's Foundation.